Lesson 2: Elements of life

• atom - the smallest unit of matter that retains all of the chemical properties of an element
• atoms are often organized into larger structures called molecules
• humans are made up of 7x10^27 atoms
• matter - refers to anything that occupies space and has mass
• elements - substances that make up matter, which have specific chemical and physical properties and cannot be broken down into other substances through ordinary chemical reactions
• Elements are made up of one type of atom
• elements - pure substances that have specific properties at a certain temperature and react in certain ways
• The four common elements in living organisms:

  • oxygen
  • carbon
  • hydrogen
  • nitrogen

  which together make up about 96% of the human body
• molecules - made up of one or more than types of atom
• Identify the following regions and subatomic particles of an atom in the image below:

  A) nucleus

  B) neutrons

  C) protons

  D) electrons

  
• An atom consists of two regions:

  1. atomic nucleus
  2. electrons
• atomic nucleus - center of the atom and contains positively charged particles called protons and neutral, uncharged, particles called neutrons
• electrons - negatively charged particles that orbit around the nucleus
• Three types of subatomic particles:

  1. protons
  2. electrons
  3. neutrons
• the number of protons determines which element an atom is
• The atomic number (Z) tells us how many protons are present in the nucleus.
• the number of electrons determines which kind of reactions the atom will undergo
• 1.67x10^-24 (1 amu) : proton & neutron mass
• neutron can change number but still the same element
• electrons - larger region ("cloud"), and can also change number but still the same element
• • Proton > Electron : +
  • Electron > Proton : -
  • Electron = Proton : uncharged
• attraction between the positively charged protons & negatively charged electrons hold the atom together
• 18% of human body weight is made up of carbon
• carbon - backbone of many important body molecules including proteins, DNA, RNA, sugars, and fats
• carbon - backbone of life because it acts as building block that can form many bonds
• organic molecules - molecules that contain carbon atoms. (except carbon dioxide and carbon monoxide)
• carbon-carbon bonds - can form covalent bonds to as many as 4 other atoms. thus, it is well suited as basic skeleton/backbone of macromolecule
• 6: Carbon atomic number

  • 6 protons
  • 6 electrons
• atomic weight - proton + neutron
• isotope - same proton, different atomic weight (different neutron)
• isobars - different proton, same atomic weight
• isotone - different proton and atomic weight, same neutron
• C^12 : most common carbon isotope
• neutral carbon has 6 electrons
• macromolecules: complex biological molecules (organic molecules: has carbon-hydrogen atoms)
• 4 : number of carbon's valence electrons
• hydrocarbons - organic molecules consisting entirely of carbon and hydrogen
• methane - simplest hydrocarbon molecule, consists of a central carbon atom bonded to four hydrogen atoms
• C-H - key structural component of most macromolecules
• Identify the corresponding hydrocarbon names

  A) methane

  B) ethane

  C) propane

  D) butane

  E) pentane

  F) hexane

  G) heptane

  H) octane

  I) nonane

  J) decane